Given that Marc Andreessen publicly vocalized support for him and his new venture, I hardly think he'll have much trouble with his career.

Not to mention that he probably owns over $200m worth of GitHub stock.

Just off the top of my head, he was allowed to resign rather than fired for cause.

I don't mean he'll have trouble getting hired - he won't. This probably won't hurt his "career" per se.

I mean he'll have trouble hiring people to work for him. I'd certainly think twice (and this is not an entirely casual statement since I'm an engineer and a startup guy) - not because of the allegations, but because the result of a careful investigation was that he made it an unpleasant place to work for some of his employees by being confrontational, disregarding complaints, and being insensitive to something that wasn't a problem for him personally. I do not want to work in a place like that, and I'd be worried that he'd do it again.

It won't stop everybody from working for him. He'll still get plenty of graduate attention. But putting together a good startup team is hard, and this kind of verdict might make it impossible.

Perhaps he resigned before the investigation was over.

It's right there in the statement:

After being presented with the results we felt Tom could no longer be an effective leader at GitHub. He offered his resignation and we accepted.